Speaking at PMQs, Sir Keir also urged Mr Johnson to resign.
He said: “Throughout this scandal the Tories have done immense damage to public trust.
“When the leader of the Scottish Conservatives said the Prime Minister should resign, the leader of the house called him a ‘lightweight’.
“English Conservatives publicly undermining the Union by treating Scotland with utter disdain.
“How much damage are the cabinet and Prime Minister prepared to do to save his skin?”
“Does the Prime Minister really not understand the damage his behaviour is doing to our country?”
Mr Johnson listed the priorities of Downing Street, including responding to the Covid backlogs and efforts to reform social care.
He went on: “They have no plan at all to fix the NHS or to fix social care. Vote Labour, wait longer.
“I hope (he) understands that though the issue he raises is important, there is simply no way, as he knows as a lawyer, that I can comment on the investigation … it’s almost as though he was in ignorance of the fact that we have a crisis on the borders of Ukraine.
“I can tell him what is going on in the Cabinet room of this country is that the UK Government is bringing the West together so that we have … the toughest possible package of sanctions to deter President Putin from what I think would be a reckless and catastrophic invasion.
“That is what this Government is doing, we’re getting on with the job and I think he needs to raise his game.”
Sir Keir also accused Mr Johnson of being distracted from the real issues by having to help save the Prime Minister.
He said: “The reality is we now have the shameful spectacle of a Prime Minister of the United Kingdom being subject to a police investigation, unable to lead the country, incapable of doing the right thing, and every day his Cabinet fail to speak out they become more and more complicit.
“What’s utterly damning, despite the huff and puff, is that this is all happening when petrol prices, the weekly shop and energy bills are going through the roof.
“Three months ago Labour suggested cutting VAT from energy bills – still the Government has failed to act. Instead of getting on with their job, they’re wheeled out to save his.
“Whatever he says in his statement later today or tomorrow won’t change the facts. Isn’t this a Prime Minister and a Government that has shown nothing but contempt for the decency, honesty and respect that define this country?”
Mr Johnson replied: “No, we love this country and we’re doing everything in our power to help this country.
“Of course he wants me out of the way, he does, I don’t deny it, for all sorts of reasons many people may want me out of the way, but I’ll tell you the reason why he wants me out of the way, it’s because he knows this Government can be trusted to deliver.”